1,1-diamino-2,2-dinitroethylene (DADNE) that is a type of insensitive explosives, is generally synthesized by hydrolyzing 4,6-dihydroxy-5,5-dinitro-2-(dinitromethylene)-2,5-dihydropyrimidine (DHDNDP) obtained from the nitration of 4,6-dihydroxy-2-methylpyrimidine (DHMP). In the hydrolysis reaction, DHDNDP is decomposed in water to give the final product, DADNE, together with the same mole number of dinitromethane and carbon dioxide as side products. Along with DADNE that is a type of explosives, the side product dinitromethane is also an explosive material which may involve explosion and decomposition at an ambient temperature and thus likely to cause problems in this hydrolysis reaction.
A hydrolysis process of DHDNDP which has been most widely used is a method proposed by N. V. Latypove et al., Organic Process Research & Development, Vol. 11, No. 1, 2007, pp. 56-59. The above method is comprised of dissolving DHDNDP into water, vigorously stirring the reaction solution overnight while maintaining the inner temperature at 20° C. or less and filtering the resulted solution. The method uses a reactor having the volume of 90 L, and other experiments or methods which used a larger reactor than said volume has not been reported so far.
However, the Latypove's method has a problem that an eruption or sudden frothing of the reactants occurs usually in about 6 hours after the beginning of the reaction, due to instability of dinitromethane generated during the hydrolysis reaction. In the meantime, this eruption or frothing was not reported in the above publication, and it is because a small amount of reactants relative to the volume of the reactor was used at low temperature. Therefore, although such eruption or frothing did not reported in said publication, the above method still has a potential problem of an eruption or frothing, due to the presence of dinitromethane together with the explosive DADNE when conducted on a large scale.